Facebook just for login

ok
what i am trying to do is Simple
I want a plugin that allow visitors To post a comment by their facebook account and to use My default theme or other plugin theme (like facebook 9 point comment system) , and to have a choice by selecting to login using the regular method (name,email,website) or to see themselves already logined by their facebooke accounts
i saw a lot of plugins but all of them r interfering with a comment system and that what i don’t want i want to use my default comment system , some of plugins i found are facebook login wedget not in the bottom of the comment area
is there any plugin can do that
thank you